I think it’s perfectly reasonable to make something useless for fun, it’s an interesting idea.
But what I’d like to understand is why there are so many of the same thing. I know I’ve seen this exact idea multiple times on HN. It’s funny the first time, but once it’s done once and the novelty is gone (which is almost immediately), what’s the point of another and another and another?
I’ve been browsing this site for a decade plus and this idea was new to me. Maybe the author is in the same boat.
Edit: I see referencnes to shadyurl in the comments and I have heard of that, but probably wouldn’t have thought of it.
A fun project doesn't need to be original, IMO.
URL Shortener is still one of the most popular System Design questions, building this project is a great way to have some experience / understanding of it, for example.
I actually forgot that this had been done before until you mentioned it.
Giving the author the benefit of the doubt, they may have not seen it before, or was bored and just wanted to make a toy.
And it seems like many in HN are in enough a similar boat to me to have up voted it to trending, so at least some people found it entertaining, so it fulfilled its purpose I suppose.
It's a good question though, and I don't think anyone really knows the answer.
The author posted this project on reddit a few days ago where they mentioned their motivation: "I have a coworker who is constantly talking about the glory days of ShadyUrl, but that website has been down for several years at this point, so I figured I would create an alternative."
One reason is that not all these websites manage to make equally "creepy" links, even though the basic idea is the same. I remember one version which was a lot more alarming than the current example, with links containing a mix of suspicious content hinting at viruses, phishing, piracy/warez sites, pornography (XXX cams), and Bitcoin scams. I don't remember that website, but the current case seems rather weak by comparison.
I think it's just someone learning something new most of the time.
I have home made url shorteners in go, rust, java, python, php, elixir, typescript, etc. why? because I'm trying the language and this kind of project touches on many things: web, databases, custom logic, how and what design patterns can I apply using as much of the language as I can to build the thing.